Based on the story, the quality that Mercury most admires in people is inventiveness. In the story, when the lumberjack lost his axe in the river, he was distressed. However, when the god Mercury appeared and asked about his distress, the lumberjack did not simply give up or continue to lament. Instead, he explained what had happened and Mercury, impressed by the lumberjack's inventiveness, gave him a golden axe to replace the one he had lost.
This shows that Mercury values people who are resourceful and creative in finding solutions to their problems. The lumberjack's ability to think outside the box and come up with a solution demonstrated his inventiveness, which earned the admiration of Mercury.
Therefore, based on the story, the quality that Mercury most admires in people is inventiveness.